[Dovecot] NFS issues [was: Dovecot-1.2 + Sieve + Managesieve on Debian]

Brian Candler B.Candler at pobox.com
Tue Mar 23 13:43:33 EET 2010

On Tue, Mar 23, 2010 at 05:42:02AM -0400, Charles Marcus wrote:
> On 2010-03-22 9:31 PM, Stan Hoeppner wrote:
> > Dovecot has built in locking support for NFS storage.
> But it has always been problematic, according to Timo.

Have you got any references on this, apart from http://wiki.dovecot.org/NFS ?

I'm looking at migrating a courier-imap installation (FreeBSD frontends,
Netapp backends, Maildir++) to dovecot. I'd be grateful of any known
pitfalls I should be looking out for.

I have done some small-scale testing and it looks fine. tcpdumping the NFS
traffic, I see that the FreeBSD frontend is sending "access" requests to
check that its local cache is not stale.  In tests with mailboxes containing
100 messages and a web IMAP frontend (atmail.org), Dovecot was generating
about 1/4 of the total NFS traffic compared to courier-imap, because of how
Dovecot creates a cache file containing the message headers.

I see a link to http://www.freebsd.org/cgi/query-pr.cgi?pr=123755 in the NFS
wiki page.  Does this problem affect only mbox over NFS, or maildir too? 

I've not observed any problem with courier-imap, although courier-imap is
much dumber about caching, and also at the moment the majority of the
userbase are on POP3 anyway.



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